A modification kit for converting an existing signage mounting structure to an electronic sign generally includes a plurality of weatherized display modules; a plurality of sign sections each having a front-facing portion and a rear-facing portion, the front facing portion defining a two dimensional array of bays arranged in a plurality of rows along a vertical direction and a plurality of columns along a horizontal direction, each bay configured to receive one of the display modules, the rear-facing portion for mounting to a surface of the existing signage mounting structure and a plurality of wiring assemblies each having a first end for coupling to a power junction located adjacent to a rear surface of one of the rear-facing portions and a plurality of power extensions for coupling the power source to the plurality of weatherized display modules.